57 Insert Interval

Posted 2020-12-29 tobeabetterpig

57 Insert Interval


https://www.youtube.com/watch?v=oWHWDI2eOHY


Sol1: use 56, insert this new interval into the sorted list, since its sorted already
No need to sort it again, so the time complexiy is o(n), for merging 
Space is still o(n)

class Solution {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
      // find the right index to insert the new interval into the intervals 
      int s = newInterval.start;
      int index = 0;
      for(Interval interval : intervals){
        if (interval.start <= s){
          index++;
        }
      }
      intervals.add(index, newInterval);
      
      List<Interval> result = new ArrayList<>();
      int start = intervals.get(0).start;
      int end = intervals.get(0).end;
      
      for(Interval interval : intervals){
        if(interval.start <= end){
          end = Math.max(end, interval.end);
        }else{
          result.add(new Interval(start, end));
          start = interval.start;
          end = interval.end;
        }
      }
      result.add(new Interval(start, end));
      return result;
    }
}








Sol2: 

很多人都用这个方法， 很多用while 写
我觉得用 if else 写 清楚
7:52 参考花花的代码

class Solution {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
      List<Interval> left = new ArrayList<>();
      List<Interval> right = new ArrayList<>();
      
      int start = newInterval.start;
      int end = newInterval.end;
      
      for(Interval interval : intervals){
        if(interval.end < start){
          left.add(interval);
        }else if(interval.start > end){
          right.add(interval);
        }else{
          start = Math.min(start, interval.start);
          end = Math.max(end, interval.end);
        }
      }
      
      List<Interval> result = new ArrayList<>();
      for(Interval interval : left){
        result.add(interval);
      }
      
      result.add(new Interval(start, end));
      
      for(Interval interval : right){
        result.add(interval);
      }
      return result;
    }
}

https://github.com/tongzhang1994/Facebook-Interview-Coding/blob/master/57.%20Insert%20Interval.java